MEMS Gyroscope Thermal Drift Compensation via Gap Width Modulation
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Solution Overview
Problem
Microelectromechanical gyroscopes face challenges in accurately compensating for output thermal drift due to manufacturing imperfections, leading to quadrature errors that affect the stability of the zero rate output, with existing solutions being either inaccurate, costly, or energy-intensive.
Innovation Solution
A microelectromechanical gyroscope design incorporating a calibration structure and a control unit that modulates the quality factor by varying the gap width between the sensing mass and the calibration structure, allowing for efficient compensation of thermal drift through electrostatic forces, enabling quick and individualized corrections without significant production or energy costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If individual calibration is performed for each gyroscope, then measurement precision is improved, but loss of time and productivity deteriorate
Solution Approach 1:
The patent modifies physical parameters of the gyroscope structure, specifically the gap width between the sensing mass and calibration structure, to change the quality factor. This allows thermal drift compensation through structural parameter adjustment rather than time-consuming digital calibration procedures, resolving the contradiction between precision and time loss.
2Measurement precision
If closed-loop dynamic compensation is implemented, then measurement precision and adaptability are improved, but device complexity and energy consumption worsen
Solution Approach 1:
The patent extracts the compensation function from complex electronic circuits and implements it through a simple mechanical calibration structure. The calibration structure with adjustable gap width provides drift compensation through physical means, eliminating the need for complex closed-loop compensation circuits and reducing overall device complexity.
Solution Approach 2:
The patent replaces electronic compensation mechanisms with a mechanical calibration structure. By adjusting the physical gap width between the sensing mass and calibration structure, the quality factor is modified to compensate for thermal drift, substituting complex electronic control with a simple mechanical adjustment.
3Ease of manufacture
If family compensation is applied, then manufacturing cost is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent enables individual parameter adjustment (gap width) during or after manufacturing, allowing each device to be optimized for its specific characteristics. This combines the cost-effectiveness of family manufacturing with the precision of individual calibration, as the structural parameter can be adjusted without requiring complex individual calibration procedures.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces the residual drift in the zero rate output, improving the accuracy and stability of the gyroscope's performance while being cost-effective and energy-efficient, allowing for both initial and ongoing calibration throughout the device's lifespan.
Implementation Method 1
The calibration structure is subject to an electrostatic force of intensity dependent on the bias of the calibration electrode
Data Source
Figure 1~2
Figure 3~5
Figure 6~7
AI summary
A microelectromechanical gyroscope includes: the support structure (6); a sensing mass (3), coupled to the support structure (6) with degrees of freedom along a driving direction (DD) and a sensing direction (DS) perpendicular to each other; and a calibration structure (5) facing the sensing mass (3) and separated from the sensing mass (3) by a gap (21) having an average width (W), the calibration structure (5) being movable with respect to the sensing mass (3) so that displacements of the calibration structure (5) cause variations in the average width (W) of the gap (21) . A calibration actuator (20, 30) controls a relative position of the calibration structure (5) with respect to the sensing mass (3) and the average width (W) of the gap (21).